The present invention relates generally to the separation of blood into its components such as red blood cells and plasma. More particularly, the present invention relates to the separation and collection of red blood cells whereby the red blood cells remain viable during extended storage.
Blood may be separated into one or more of its components or fractions such as red cells, white cells, platelets and plasma, and one or more of the blood components or fractions may be collected. In typical blood collection procedures, whole blood is withdrawn from a donor or patient, anticoagulant is added to the withdrawn whole blood and one or more desired components or fractions are separated from the anticoagulated whole blood. A separated component may be administered, immediately or soon thereafter, to a patient in need of the particular component. Alternatively, the collected component may be stored for a period of time until it is required for transfusion.
Blood collection procedures and systems are often referred to as either xe2x80x9cmanualxe2x80x9d or xe2x80x9cautomated.xe2x80x9d In xe2x80x9cmanualxe2x80x9d blood collection procedures, whole blood is withdrawn from a donor and collected in a container that typically includes an amount of anticoagulant. After the collection, the donor is free to leave and the collected unit of whole blood is then subjected to a separation procedure, such as centrifugation.
In xe2x80x9cautomatedxe2x80x9d blood collection procedures, the donor is directly connected to a blood collection device and whole blood is withdrawn from the donor. A desired component is separated and collected while the remaining components may be returned to the donor. Automated blood collection procedures have the advantage over manual blood collection procedures in that the initial collection of whole blood and the separation of the whole blood into the desired components or fractions can be achieved in a single procedure.
Instruments used to perform automated blood collection procedures, such as those described above, typically include a reusable hardware portion and a disposable tubing portion intended for one-time use only. The hardware portion may include pumps, such as peristaltic pumps for (1) withdrawing whole blood from a donor or patient, (2) introducing anticoagulant into the whole blood (3) introducing blood into a separation device for separating blood into its components and (4) withdrawing one or more blood components from the separation device for later use or for return to the donor or patient. Either the hardware portion or the disposable tubing portion may include the separation device which, for example, can be a rotating centrifuge as described in U.S. Pat. No. 4,146,172 or a rotating membrane as described in U.S. Pat. No. 4,753,729. The disposable tubing portion typically includes, among other things, the venepuncture needle that is inserted into the donor and through which the whole blood is withdrawn, plastic tubing which transports the blood and/or blood components to and from the donor or patient and to and from the separation device. If a desired blood component is to be collected, the disposable tubing portion may also include plastic bags for collecting the desired blood component(s). Typically, the segments of the tubing are threaded over and engaged by the peristaltic pumps of the instrument. Peristaltic pumps include rotating members (rotors) driven by motors. Rotation of the pump rotors squeezes the tubing and consequently draws and pushes the blood or blood components through the tubing and through the system.
Examples of commercially available automated blood separation and collection systems are the CS-3000(copyright) Plus and the Amicus(copyright), both sold by Baxter Healthcare Corporation of Deerfield, Ill. The CS-3000(copyright) Plus and the Amicus(copyright) are automated systems for the separation and collection of blood components and/or fractions such as platelets, plasma, and the like. Another example of a commercially available automated blood separation and collection device is the Autopheresis-C(copyright), also sold by Baxter Healthcare Corporation. The Autopheresis C(copyright) is an automated system for the collection of plasma.
Although, commercially available devices for the automated collection of platelets, plasma, stem cells and other components are known, automated red cell collection systems have only recently been introduced. Presently, the collection of red cells is performed using the manual procedures described above.
With respect to manually collected red cells, it is known that red cells can be stored for extended periods of time (e.g. beyond 24 hours) when combined with a suitable storage media. For example, in U.S. Pat. No. 5,248,506, which is also incorporated by reference herein, manual collection of red cells from whole blood anticoagulated with a citrate-phosphate dextrose (CPD) anticoagulant and storage of the red blood cells in a red cell storage media is described. More specifically, U.S. Pat. No. 5,248,506 describes storage of red blood cells in a plasma-free storage medium that maintains the function and viability of the red cells for an extended period of time, e.g. (at least 42 days).
Factors that may affect the viability and function of stored red blood cells include ATP levels, 2,3 DPG levels, pH and the hemolysis of the red blood cells. For example, ATP (adenosine triphosphate) provides energy that is required to maintain the shape and volume of red blood cells. ATP is produced when the red blood cells metabolize glucose. Reduced ATP levels result in increased fragility of the red blood cells and, consequently, reduced viability. 2,3 diphosphoglycerate (DPG) plays a role in the red blood cell""s ability to release oxygen. When 2,3 DPG levels decrease, the efficiency of oxygen release is impaired.
The pH of red blood cells must also be maintained. As the red cells break down glucose and form lactic acid, the pH of the red cell product decreases and the red blood cells undesirably become more acidic. Finally, as red blood cells are stored, they undergo hemolysis. xe2x80x9cHemolysisxe2x80x9d refers to the destruction of the red blood cell membrane.
Storage solutions for storing components such as red blood cells often contain nutrients and other preservatives intended to preserve the viability of red blood cells by helping maintain acceptable ATP, 2,3-DPG and pH levels and suppressing the hemolysis of red blood cells. Although there have been several reported attempts at providing methods for preserving the viability of red blood cells during storage, further improvement in ATP levels and further reduction in hemolysis (as well as other storage parameters) is, nonetheless, still desirable.
There are several aspects to the present invention. In accordance with one aspect of the present invention, a method for collecting red blood cells is provided. The method includes providing a quantity of whole blood and combining the whole blood with a quantity of an anticoagulant. The anticoagulant includes citric acid, trisodium citrate and dextrose. The anticoagulated whole blood is separated to provide a red blood cell concentrate. The red blood cell concentrate is combined with a quantity of a solution that includes dextrose, sodium chloride, adenine and mannitol.
In accordance with another aspect of the present invention, the anticoagulated whole blood is separated to provided a red cell concentrate comprising between approximately 160-240 ml of red blood cells. The method further includes adding approximately 80-120 ml of a solution that may include, among other things, adenine, mannitol, dextrose and sodium chloride.
In accordance with another aspect of the present invention, viable red blood cells may be provided by a method which includes, among other things, establishing fluid communication between a donor and a blood separation device and removing a quantity of whole blood from a donor and combining the whole blood with a selected quantity of a phosphate-free anticoagulant. The anticoagulated whole blood is introduced into the separation device where it is separated into its components, where one of the components is concentrated red blood cells. At least a portion of at least one of the components is returned to the donor while maintaining fluid communication between the donor and the separation device. The method also includes collecting at least a portion of the separated concentrated red blood cells in a container and storing the concentrated red blood cells in a selected quantity of a solution comprising dextrose, adenine and mannitol.
In accordance with another aspect of the present invention, the method for providing viable red blood cells may include providing a separation device which includes a driven element including a separation zone to receive the anticoagulated whole blood. The method includes coupling a drive element to the driven element to cause a separation of said whole blood in the separation zone into plasma and concentrated red blood cells. The method further includes coupling an inlet pump to the driven element to convey into the separation zone whole blood from a donor selected from the population of blood donors, wherein the whole blood of the selected blood donor having a known beginning hematocrit value that varies within the population of blood donors, according to the morphology of the selected blood donor. In accordance with a further aspect of the present invention, the method includes commanding the inlet pump element and the drive element as a function of the known beginning hematocrit value to obtain concentrated red blood cells having an end hematocrit value that remains substantially constant for the population of blood donors despite variances in the known beginning hematocrit value according to the morphology of the selected blood donors.